All,I do have a Vaio Notebook (XP Professional) containing a Toshiba MK 1234 GSX 120GB Harddrive, Interface is a Serial ATA-150.I thinking of a upgrade with an Intel SSD X25-M Postville 80GB SSD, but this has as a SATA II interface. Does anyone knows if that´s gonna work at all beside the fact that I cannot fully realize the speed of the SSD ? Other Options?

Yes, it is going to work. I've got one in a 3y old Thinkpad which is also limited to SATA I. So you won't get 200Mb/sec speeds, but I do perceive a 10-20% speed gain over my old 7200 rpm HDD. Your old drive looks slower, that means you'll notice even more of an improvement.